The present invention relates in general to music systems and in particular to an apparatus for producing a chord progression.
Apparatus for providing a progression or succession of chords available for a given melody are known. Examples are disclosed in Japanese patent application laid open to public as Sho 58-87593, and U.S. Pat. No. 4,539,882.
Such apparatus have been commonly built in musical instruments such as keyboard instruments. In a typical operation, melody information is provided by playing (operating) a keyboard, and recorded into a memory in the instrument. The recorded melody information is then analyzed for each segment (e.g., measure) thereof to determine a harmony or chord progression implied by the melody. The chord progression thus obtained may be utilized to provide an automatic accompaniment to the melody in a synchronous relation while the melody is being played again from the keyboard.
Because of their principles, the chord progression apparatus described above need a melody of a music piece to obtain a chord progression, and may be better referred to as melody harmonization apparatus.
Apparatus for producing or creating a chord progression of a music piece in an environment without any melody or melodic contents must take quite a different approach from that of the melody harmonization apparatus. An apparatus for producing a chord progression without requiring any melodic information was proposed by the present inventor in Japanese patent application Sho 63-90226, filed on Apr. 14, 1988 and assigned to the same assignee as the present application. This Japanese application discloses an apparatus comprising means for collecting chord progressions of many existing music pieces. For each two-chord order or permutation in the collected chord progressions, a frequency measurement device evaluates a number of transitions from the first to the second chord to provide a frequency table of two-chord transitions. In operation, a chord progression is developed on a one-chord-after-another basis according to the frequency table in combination with a random number generator. Given a current chord, the next chord is determined by a chord with the maximum value obtained from combining the value of the frequency of the chord in the frequency table with the value of a number generated at random. A relative weight of the random component is made adjustable by the user.
While the above-mentioned apparatus can produce a chord progression by a chain of chords without requiring any melody, it has several disadvantages as follows:
(1) The apparatus significantly relies on the frequency table which is a statistic parameter of collected or sampled chord progressions. Therefore, chord progression generated from the same frequency table in a number of times will be made similar to one other, though depending on the relative weight of the random component affecting the next chord determination. Hence, new collection of chord progressions, from which a new frequency table is derived, is required to obtain a substantially different chord progression.
(2) The full automatic production of a chord progression leaves no or little room for the user to take active participation or the initiative in creating a chord progression.
(3) The next succeeding chord is essentially determined by the most likelihood of the transition from the current chord. This is a short-term (i.e., two-chord length) control of the chord progression generation, lacking in a long-term or structural control to assure musicality in the generated chord progression.